As I do highway and land surveying work as opposed to electrical work for a living, maybe there's something I do not understand about the 42-circuit limitation spelled out in NEC 408.15 for lighting and appliance panelboards. It just seems like a totally arbitrary limit when the panelboard's load cannot exceed the ampacity of the main disconnect anyway (or at least it shouldn't be able to).

I've read other posts in this forum mentioning the limitation based on a fire investigation done many years ago, my memory ain't like it was when I was younger but I think it was a 1928 Chicago fire or something like that. Yet, our neighbors to the north apparently can obtain lighting/appliance panelboards up to 84 circuit capacity- I seriously doubt there has been an increase in fires for reasons mentioned in the first paragraph.

With all of the dedicated circuits now required by the NEC, I believe this limitation should be either substantially increased or eliminated as long as the main OCP device protecting such a panelboard is in keeping with its rated capacity.

Since I do live within a few miles from the Canadian border, maybe I could smuggle one across- then again, it may not be able to handle non-metric loads :-)

This forum is a great place indeed to learn and communicate; kudos to the hosts!!!

Yeah you got be careful mixing non metric and metric electricity.

I spend a lot of time in buildings with many dedicated ciruits.

We run into the 42 circuit limit all the time before we run out of electrical capacity

What we do is use double or triple tub panels 84, or 126 circuits respectively on one feeder.

I agree that 42 seems to be just an arbitrary number but I like the limit.

42 circuits worth of branch circuit wiring in one tub is enough for me, 126 circuits spread out in three tubs is nice to work with.

Just my opinion, Bob

Some panels are manufactured now with more than 42 circuit spaces. Square D makes one with a low voltage control feature for lighting, and there are around 46 or 48 spaces, I can't remember.

As far as residential goes, a dozen circuits would be a lot here. There are still plenty of homes wired in the 1950s/60s with only 4 circuits!


Love that name!



[This message has been edited by pauluk (edited 03-06-2004).]

The spaces may be there but I doubt you can put breakers in the spaces.


The spaces are probably for elements of the control system.

Bob, I realize that the code says 42, but these panels were loaded to over 42, with guts from the factory, all spaces occupied. I didn't notice at first till we were finishing numbering the circuits. When I asked the foreman, he just said that's what they gave us, that's what we're using. The prints were all engineered like that, and I never saw the inspector's response, if any.

Well that is interesting. hmmmmmm?

I do not think I would have installed it without checking further on this.

The panels we have assembled for us are put together many times at panel shops of large distributors, I would not assume that just because they built it that it complies.

Don I know you have said there are times we can exceed 42 OCPDs would this be one of those time?

The use of the word 'and' is suspicious. Sounds to me like a panel supplying a combination of lighting and appliance loads has a 42-circuit limit. Whereas a dedicated lighting panel could be larger. Otherwise 'or' should be used in the ruling.

What do you guys think?

I never looked at it that way, and it's possible that you have something there, bu the only definitions I see for the different types of panelboards is in 408.14(A)and (B). Looks like it's either "lighting and appliance" or "power".

After the paragraph Bob quoted from 408.15, it says "a lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more than overcurrent devices than that number for which the panelboard was designed, rated, and approved." These panelboards had nothing to prevent more than 42 breakers from being installed; they looked like they were designed to hold all of them (hoever many that was, I forgot--44-46-48, whatever.)

Power panels do not have the 42 circuit limit like "lighting and appliance branch circuit panels" do. The types of loads served do not determine the type of panel.
The panelboard in question may have been intended as a power panelboard and it is being illegally used as a lighting and appliance branch circuit panelboard.
Don

It was definitely a lighting panelboard. It was made by Square D, Power-link I think, and had low-voltage contol busses on the sides, for remote switching of the lighting circuits.

resqcapt19 ---

If I read your code section right:

1) I can build a 431 circuit panel,

2) Install 43 lighting circuits, and

3) fill the remaining spaces with breakers with ratings over 30 amps.

I think that complies with the letter of that section (but not the spirit).

The 42 circuit limit is foolish, but due to voltage drop over distance in most cases a better solution is to provide subpanels remote from the main panel.

Hmmm... even though I'm planning on only a 200 amp service upgrade (up from 100 amp in a 2200 sq. foot house built in 1978), the twin subpanel idea sounds like a good one. I could put the 240-volt circuits in one panel and the 120's in the other, with a 200 amp main disconnect ahead of them. This would give me plenty of expansion opportunity. It might raise the AHJ's eyebrows, though as it might be considered overkill for such a house. I still am a big fan of planning for the future as best as can be done.

Square D makes 54 pole NQOD panelboards for sale in the US. I presume that, if you use one as a "lighting and appliance branch-circuit panelboard" you are not permitted to install more than 42 poles of breakers.

As someone already mentioned on the thread, for export to Canada they make NQOD panelboards with as many as 84 spaces.

It looks like an old topic resurrected...one thing that was noted in some Handbook somewhere is that a panel used to supply only circuits of >30A is _not_ a 'lighting and appliance panelboard', even if _all_ of those >30A circuits are used to feed lights.

-Jon

I've heard stories of people smuggling toilet cisterns in from Canada to get round the federal water-saving limit (what is it now, 1.2 gallons maximum per flush?).

WIth cisterns and panelboards, I wonder what will be next!

The 42 circuit limit did indeed result from a fire in the Waldorf-Astoria Hotel in New York in 1928. This was a lighting panel wired with type R wire. This story was confirmed by the late Anthony Montouri, Chief Inspector, New York Board of Fire Underwriters. It was judged at the time that there was too much insulation and braid in one enclosure, and the 1933 NEC in Section 1303g. established the 42 circuit limit. It may have been over-reacting. To change this would require extensive testing and I doubt there is any interest willing to put up the money for such an investigatrion.
Creighton

Thought they were going to open up the 84 circuit panels for the US after they force us all to have AFCI everything. Isn't that the current rumor?

It might be more hazardous to fall in a panel that big.

Sometimes have trouble trying to get 24 circuits into the top, and bottom through framing. Every panel would need a cable tray to get it all over to the panel without turning the building into swiss cheese.

How many are using the 30 space 100A Loadcenter?

Les